Humans have a curiosity to look behind things. For example, a person may look behind doors, peek out of windows, and open up presents. The sense of anticipation followed by surprise associated with such an act creates feelings of enjoyment and satisfaction at finding what was initially hidden from plain view. This curiosity does not diminish when one is reading a book or magazine. In both cases, the reader will often be curious to learn the meaning of a word or the history behind a subject presented in the text of the book or magazine. For example, a child reading the Harry Potter® book series may want to know the origin of the word “wizard” or brush up on the history of medieval Europe.
One way that a reader can satisfy this curiosity is by having, on hand, reference texts such as encyclopedias, dictionaries, or textbooks related to the various subjects the reader finds interesting. However, such reference texts are often expensive and cumbersome to transport and bringing such texts along whenever one is in the mood for a good story diminishes the reading experience. While electronic books (or e-books) have enabled readers to store multiple texts in one place, the reader is still required to predict which electronic reference texts are necessary to satisfy the reader's sense of curiosity going forward and to have such electronic reference texts loaded on the e-book before starting a new book or story. Unfortunately, the reader cannot always predict which reference texts will be necessary and whether such texts will satisfy his or her sense of curiosity before starting a good book.